Thyroxine (T4)


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Thyroxine (T4)


Thyroxine (T4) is the most common form of thyroid hormone that is released by the thyroid gland. Once it reaches the tissues, it is converted to another form of the thyroid hormone called triiodothyronine (T3), which is more active in regulating the body's chemical reactions.

In tests of thyroid function, a low T4 level may indicate the presence of low thyroid levels (hypothyroidism). Certain forms of liver or kidney disease may also cause a low T4 level, even though a thyroid problem may not be present.

Credits


Author Jeannette Curtis
Author Caroline Rea, RN, BS, MS
Editor Kathleen M. Ariss, MS
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Tracy Landauer
Associate Editor Pat Truman
Primary Medical Reviewer Patrice Burgess, MD

- Family Medicine
Primary Medical Reviewer Adam Husney, MD

- Family Medicine
Primary Medical Reviewer Kathleen Romito, MD

- Family Medicine
Last Updated May 25, 2007

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Last updated: May 25, 2007
Author: Caroline Rea, RN, BS, MS
Reviewed By: Kathleen Romito, MD - Family Medicine
Editors: Susan Van Houten, RN, BSN, MBA, Pat Truman

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